Synthesis and Diels-Alder reactions of 4-vinylimidazoles

Organic Letters

Volumn 3, Issue 9, 2001, Pages 1319-1322

  Lovely, Carl J ^a   Du, Hongwang ^a   Dias, H V Rasika ^a  

^a UNIVERSITY OF TEXAS AT ARLINGTON   (United States)

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ARTICLE;

EID: 0001512880     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol015687m     Document Type: Article

References (29)

1. Kinnel, R.; Gehrken, H.-P.; Swali, R.; Skoropowski, G.; Scheuer, P. J. J. Org. Chem. 1998, 63, 3281.
2. For synthetic approaches to palau'amine and related molecules, see: (a) Starr, J. T.; Koch, G.; Carreira, E. M. J. Am. Chem. Soc. 2000, 112, 8793.
3. (b) Overman, L. E.; Rogers, B. N.; Tellow, J. E.; Trenkle, W. C. J. Am. Chem. Soc. 1997, 119, 7159.
4. (c) Dilley, A. S.; Romo, D. Org. Lett., submitted for publication.
5. Sepulveda-Arques, J.; Abarca-Gonzalez, B.; Medio-Simon, M. Advances in Heterocyclic Chemistry; Katritzky, A. R., Ed.; Academic: San Diego, 1995; Vol. 63, p 339.
6. Walters, M. A.; Lee, M. D. Tetrahedron Lett. 1994, 35, 8307.
7. Deghati, P. Y. F.; Wanner, M. J.; Koomen, G.-J. Tetrahedron Lett. 1998, 39, 4561.
8. Kosaka, K.; Maruyama, K.; Nakamura, H.; Ikeda, M. J. Heterocycl. Chem. 1991, 28, 1941.
9. For studies relating to Diels - Alder reactions of 2-vinylimidazoles, see: (a) Abarca-Gonzalez, B.; Jones, R. A.; Medio-Simon, M.; Quilez-Pardo, J.; Sepulveda-Arques, J.; Zaballos-Garcia, E. Synth. Commun. 1990, 20, 321.
10. (b) Rothenburg, A. S.; Daulplaise, D. L.; Panzer, H. P. Angew. Chem., Int. Ed. Engl. 1983, 22, 560.
11. Iddon, B.; Lim, B. L. J. Chem. Soc., Perkin Trans. 1 1983, 735.
12. Kirk, K. L. J. Heterocycl. Chem. 1985, 22, 57.
13. (a) Cliff, M. D.; Pyne, S. G. J. Org. Chem. 1995, 60, 2378.
14. (b) Cliff, M. D.; Pyne, S. G. J. Org. Chem. 1997, 62, 1023.
15. (c) Cliff, M. D.; Pyne, S. G. Tetrahedron 1996, 52, 13703.
16. (a) Altman, J.; Wilchek, M. J. Heterocycl. Chem. 1988, 25, 915.
17. (b) Kokosa, J. M.; Szafasz, R. A.; Tagupa, E. J. Org. Chem 1983, 48, 3605.
18. It is believed that this is due to the lability of the trityl-protecting group at elevated temperature.
19. In addition, attempts to engage this diene with activated acyclic dieneophiles have been unsuccessful in large part as a result of steric hindrance.
20. Du, H.; Lovely, C. J.; Dias, H. V. R. Tetrahedron Lett., manuscript in preparation.
21. The introduction of the dimethylsulfamoyl group can be problematic with respect to the regioselectivity when 4(5)-iodoimidazole is used; therefore it was prepared in an analogous fashion to the MOM-protected derivative. See: Bhagavatula, L.; Premchandran, R. H.; Plata, D. J.; King, S. A.; Morton, H. E. Heterocycles 2000, 53, 729.
22. Carver, D. S.; Lindell, S. D.; Saville-Stones, E. A. Tetrahedron 1997, 53, 14481.
23. Abarbri, M.; Thibonnet, J.; Bérillon, L.; Dehmel, F.; Rottländer, M.; Knochel, P. J. Org. Chem. 2000, 65, 4618.
24. The identity of this regioisomer was confirmed through an NOE experiment.
25. Janin, Y. L.; Aubertin, A.-M.; Chiaroni, A.; Riche, C.; Monneret, C.; Bisagni, E.; Grierson, D. S. Tetrahedron 1996, 52, 15157.
26. NOESY experiments were used to support this supposition, and these experiments revealed cross-peaks due to an NOE between C8a and C8b in both 22b and 22c.
27. The trace formation of exo adducts cannot be excluded. Although there are traces of other components produced in these reactions, we have not isolated any other products from the reaction mixtures. See ref 14.
28. We have found with electron-donating substituents on N1 that the enamines have an enhanced tendency to aromatize, although the enamine can be isolated. In addition, these enamines are prone to further reactions, see ref 14.
29. 3, 60 °C), 16% of the aromatized benzimidazole was obtained. However, the addition of p-TsOH increased this yield to 41%.